135. Solving a chemistry problem

1. To construct a calibration graph for the determination of copper in solution on a single-beam photometer, the following data were obtained:
Copper content, mg/l 0 0.1 0.2 0.5 0.75 1.0
Galvanometer readings 80 67.5 57.0 34.5 28.5 15.0
Build a calibration graph in the coordinate systems optical density - copper concentration and galvanometer deviation - copper concentration and determine the copper content in the test solution if the galvanometer deviation is 45.5 divisions.